During May Day, with the release of the movie "King of the Long Sky", this military-themed film reflecting Air Force test pilots aroused the audience's strong interest in test flights. The purpose of the test flight is to draw red lines for the flight of the aircraft.
The swallowing test includes swallowing bird, ice swallowing, sand swallowing, swallowing liquid water in the atmosphere, swallowing oil test, etc., the purpose is to let the engine also taste the taste of "sweet and sour", and see how "belly" and "spicy" the engine is.